Piston



Feb. 6, 1934.- A,'| NELSON A 1,945994 l PISTON Filed Aug. 15, `198 {Sheets-Sheet 2 Patented Feb. 6, 1934 PISTON Adolph L. Nelson, Detroit, Mich., assignor to Bohn Aluminum & Brass (Lorporation,4 Detroit,

Mich.

Application August 15, 1928. Serial No. 299,720

14 Claims.

This invention relates to pistons, and particularly to pistons for use in automobile engines.

The invention is especially adapted to pistons in which the head and depending piers are formed of light-weight metal, and in whicha pair of struts extend across the skirt to exert an inuence on the rate of expansion of the bearing faces of the skirt.

A principal object of the invention is to provide a piston in which integral, homogeneous ties extend along'the struts and connect each bearing face to each pier, the ties along the outer face of the struts being of different size, and hence of diierent pulling power on contraction, from the ties along the inner face.

The invention also contemplates a structure in which each strut is held by three separate, complete bands of the material of the piston skirt.

Further objectsand advantages of the invention will become apparent as the description proceeds.

While preferred embodiments have been disclosed for purposes of illustration, it should be understood that various changes may be made in the structure without departing from the spirit and scope of the invention as hereinafter set forth and claimed.

In the drawings:

Fig. 1 is a side elevation of a piston embodying the invention.

Fig. 2 is a section on line 2-2 of Fig. 1. Fig. 3 is a section taken through the strut and ties.

Fig. 4 is a side elevation of a modified form. Fig. 5 is a side'elevation of a. further modification.

Fig. 6 is a section taken on line 6-6 of Fig. 4. Referring to the drawings more particularly, the reference numeral 10 indicates the head of 10 the piston, which is preferably formed of a lightweight metal, such as an alloy of aluminum, and numeral 11 is applied to integral piers depending from the head and formed with piston pin bosses 12. The skirt, which may also be formed of 5 light-weight metal, comprises a lower circular portion 13 and cylinder-bearing portions 14 extending upwardly from the circular portion. The cylinder-bearing portions are held in spaced relation by a pair of struts 15 formed of a material i0 less expansible than that of the piers, such as steel. Each strut is a plate-like member, and is apertured in the middle as at 16 to provide an opening for the piston pin boss. The strut is also formed 5 with indentations 23 on both upper and lower edges, these indentations helping to strut in the pier.

The lower circular portion is slotted below each piston pin boss as at 22, thereby forming separate, free Wings 24.

Each cylinder-bearing portion is connected to each pier by ties 25 and 26, which are cast homogeneous with the pier and with the cylinder-bearing portions. The ties 26, formed on the inside of the strut, are heavier than the ties 25 on the outside of the strut. This construction causes the piston to expand faster on diameter A-'A than on diameter B-B when the piston becomes heated under operating temperatures.

The cause of this action lies in the fact that when the piston cools after casting the heavier tie 26 pulls inwardly more strongly than the tie 25, and hence the diameter A-A contracts Y faster than diameter B-B. Now on heating the reverse action takes place, and advantage can be taken of this action to give the piston skirt a more even bearing on the cylinder wall than would be possible without this differential tie action.

It would also be possible to place the heavier tie on the outside in a case where it was found advantageous to have the diameter A-A expand more slowly than diameter B-B as the piston warms up in operation. Without the ties 25 and 26 the diameter A-A expands less rapidly than diameter B-B. This also holds true when tie 25 is the same strength as tie 26. By proportioning the widths of the ties properly the expansion on diameter A-A may be made to equal that on diameter B-B. A very slight increase of diameter A-A expansion over that of diameter B-B gives the best results relative to a good working bearing von the skirt.

The strength of the ties may also be altered by keeping the width the same and changing the thickness.

In the modification of Fig. 4 the ties 25 and 26 extend downwardly and join the free wings 24. This arrangement shortens the unsupported 10 length of the wings 24 and hence makes them stiffer and more readily machinable. Furthermore the expansion of the skirt on the diameter passing through wings on opposite sides of the skirt will be more positive, giving the piston better side-wise support in the cylinder.

In this modication each strut is held by three separate complete bands of skirt material, as shown in Fig. 6. l One of these ties surrounds the part of the strut lying above the aperture 16,

anchor the and one is formed by each pair of ties 25 and 26.

In the species illustrated in Fig. 5 one of the pairs of the -ties extends straight to the side, as in Fig. 1, while the other pair extends downwardly, as in Fig. 4. In this case the slots 22, which are located midway between points 27 and 28, are spaced diierently on the lower circular part.

For the purpose of the discription and claims the piston is taken as standing on its open end as in Figure 1 of the drawings.

I claim:

1. Ai piston comprising a head, piers depending from the head, ,cylinder-bearing portions on opposite sides of the piston, and a pair of struts extending between the cylinder-bearing portions, there being an interior homogeneous tie between each cylinder-bearing portion and each pier and extending along the inner side of a strut, and an exterior homogeneous tie between each cylinder-bearing portion and each `pier and extending along the outer side of a strut, the interior ties being of a cross-sectional size diierent from that of the exterior ties.

2. A piston comprising a head formed of lightweight material, piers depending from the head,

cylinder-bearing portionsbn opposite sides of the piston, and a pair of struts of material less expansible than the material of the head, the struts extending between the cylinder-bearing portions, there being an interior homogeneous tie between each cylinder-bearing portion and each pier and extending along the inner side of a strut, and an exterior homogeneous tie between eachcylinder-bearing portion and each pier and extending along the outer side of a strut, the interior ties being of a cross sectional size diierent from that of the exterior ties.

3. A piston comprising a head, piers depending from the head, cylinder-beaming portions on opposite sides )of the piston, and a pair of struts extending between the cylinder-bearing portions, there being an interior homogeneous tie between each cylinder-bearing portion and each pier and extending along the inner side of a strut, and an exterior homogeneous tie between each cylinder-bearing portion and each pier and extending along the puter side of a strut, the interior ties being of a larger crosssectional size than the exteriorties.

4. /A piston comprising a head formed of lightweight material, piers depending from the head, cylinder-bearing portions on opposite sides of the piston, and a pair of struts of material less expansible than the material of the head, the struts extending between the cylinder-bearing portions, there being an interior homogeneous tie between each cylinder-bearing portion and each pier and extending along the irmer side of a strut, and an exterior homogeneous tie between each cylinder-bearing portion and each pier and extending along the outer' side of a strut, the interior ties being of a larger crosssectional size than the exterior ties. y

5. A piston comprising a head, piers depending from the head and having piston pin bosses formed therein, cylinder-bearing portions on opposite sides of the piston, a lower circular portion slotted below the pin bosses to `form free wings, a pair of struts extending between the cylinderbearing portions, a pair of ties extending from each pier along each strut, the ties being homogeneous with the piers, and joining with the free wings of the lower circular portion.

6. A piston comprising a head, piers depending from the head, cylinder-bearing portions on opposite sides of the piston, and a pair of struts extending between the cylinder-bearing portions, there being an interior homogeneous tie between each cylinder-bearing portion and each pier and extending at a downward angle between the vertical and the horizontal along the inner side of a strut, and an exterior homogeneous tie between each cylinder-bearing portion and each pier and extending at a downward angle between the vertical and the horizontal along the outer side of a strut, the interior ties being of a cross-sectional size different from that of the exterior ties.

7.C A piston comprising a head formed of lightweight material, piers depending from the head, cylinder-bearing portions on opposite sides of the piston and a pair of struts of material less expansible than the material of the head, the struts extending between the cylinder-bearing portions, there being an interior homogeneous tie between each cylinder-bearing portion and each pier and extending at a downward angle between the vertical and the Yhorizontal valong the inner side of a strut, and an exterior homogeneous tie between each cylinder-bearing portion and each pier and extending at a downward angle between the vertical and the horizontal along the outer side of a strut, the interior ties being of a cross sectional size diierent from that of the exterior ties.

8. A piston comprising a head, piers depending from the head, cylinder-bearing portions on opposite sides of the piston, and a pair of struts extending between the cylinder-bearing portions, there being an interior homogeneous tie between each cylinder-bearing portion and each pier and extending at a downward angle between the vertical and the horizontal along the inner side of a strut, and an exterior homogeneous tie between each cylinder-bearing portion and each pier and extending at adownward angle between the vertical and the horizontal along the outer side of a strut, the interior ties being of a larger crosssectional size than the exterior ties.

9. A piston comprising a head formed'of light- Y weight material, piers depending from the head, cylinder-bearing portions on opposite sides of the piston, and a pair of struts of material less expansible than the material of the head, the struts extending between the cylinder-bearing portions,

there being an interior homogeneous tie between each cylinder-bearing portion and each pier. and extending at a downward angle between the vertical and the horizontal along the inner side of a strut, and an exterior homogeneous tie between each cylinder-bearing portion and each pier and extending at a downward angle between the vertical and the horizontal along the outer side of a strut, the interior ties being of a larger crosssectional size than the exterior ties.

10. A piston comprising a head, piers depending from the head and having piston pin bosses formed therein, cylinder-bearing portions on opposite sides of the piston, a lower circular portion slotted below the pin bosses to form free wings, a pair of struts extending between the cylinderbearing portions, a pair of ties extending at downward divergent angles from each pier along each strut, the ties being homogeneous with the piers, and joining with the free wings of the lower circular portion.

11. A piston comprising a head, piers depend-A ing from the head, cylinder-bearing portions on opposite sides of the piston, a pair of struts extending between the cylinderbearing portions, 150

each strut being held by only three separate, complete bands of the material of the piers.`

12. A piston comprising a head, piers depending from the head and carrying piston pin bosses, cylinder-bearing portions on opposite sides of the piston, a pair of struts extending between the cylinder-bearing portions both above and below the openings of the pin bosses, each strut being formed with an aperture for the piston pin, each strut being engaged by only three separate, complete bands of the material of the piers, said bands passing through the aperture in the strut.

13. A piston comprising a head, piers depending from the head and carrying piston pin bosses, cylinder-bearing portions on opposite sides of the piston, the head, piers and cylinder-bearing portions being formed of light-weight material, a pair of struts of material less expansible than the material of the head extending between the cylinner-bearing portions both above and below the openings of the pin bosses, each strut being formed with an aperture for the piston pin, each strut engaged by only three separate, complete bands of the material of the piers, said bands passing through the aperture in the strut.

14. A piston comprising a head, piers depending from the head, cylinder-bearing portions on opposite sides of the piston, a pair of struts of material dierent from the material of` the cylinder-bearing portions, said struts extending between the cylinder-bearing portions, the upper part of each strut being surrounded by a band of the material of the pier, and only two additional `comp1ete bands, each of said additional bands being homogeneous with a pier and with a cylinder-bearing portion and surrounding a part of the strut.

ADOLPH L. NELSON. 

